1. Field of the Invention
This invention relates a washing machine provided with means for preventing propagation of microorganism such as fungi and bacteria so that laundry can sanitarily be washed.
2. Description of the Prior Art
Household washing machines have conventionally been constructed so that a suitable amount of detergent and a predetermined amount of water from a service water line are supplied into a wash tub containing laundry to be washed, and agitation is subsequently caused in the wash tub in order that the laundry may be cleaned. A calcium component contained in the service water acts upon a surface active agent contained in the detergent such that an insoluble metal soap is produced. Parts of the metal soap adhere to the wash tub. Production of the metal soap is conspicuous when soap powder comprising a higher fatty acid sodium is used as the washing detergent.
An automatic washing machine usually has a double tub structure, namely, comprises an outer water-receiving tub and an inner wash tub provided in the water-receiving tub and also serving as a spinning tub for dehydration. In this type of washing machine, the laundry is not brought into contact with an outer circumferential face of the wash tub and an inner circumferential face of the water-receiving tub although washing liquid is caused to flow through a space defined therebetween. accordingly, the metal soap adheres to the outer circumferential face of the wash tub and the inner circumferential face of the water-receiving tub to be piled up.
When the metal soap is piled up on the outer circumferential face of the wash tub etc., as described above, flocks or stains separated from the laundry easily adhere to the piled metal soap, whereupon a complex of the metal soap, flocks, stains, etc., is produced in the wash tub. When adhering to the complex, spores of fungi (mold) grow up into sporophytes which produce spores causing stains. The spores further produce an offensive smell due to metabolite. Additionally, the complex with mold adherent thereto comes off from the wash tub thereby to adhere to the laundry.
The water-receiving tub and the wash tub cannot usually be disassembled for cleaning by an ordinary user. Further, since reinforcing ribs are provided on the wash and water-receiving tubs for reinforcement, surfaces of these tubs are rugged. Accordingly, the metal soap is easily piled up on these tubs.
On the other hand, spores of a number of fungi contained in a human body and in an open air are adherent to the laundry (clothes). The spores remain in the wash tub after the laundry has been washed out. This results in an increased time for drying the laundry. Further, when the laundry is left wet for a long time, the spores adherent to the laundry grow up such that the laundry is tinged with yellow or smells offensive.
Water used for the bathing purpose is sometimes re-used for the clothes washing purpose in Japan. Recent automatic washing machines are provided with a washing course in which water remaining in a bathtub is supplied into the washing machine so as to be used for washing for the purpose of water saving. However, since the remaining water is considered to contain a number of fungi, the laundry is tinged with yellow or smells offensive more easily in the case where the remaining water is used for washing than in the case where the water from the service water line is used for washing.
Therefore, an object of the present invention is to provide a washing machine in which propagation of fungi can be prevented in the wash tub and the laundry can be prevented from being tinged with yellow or smelling offensive such that the laundry can sanitarily be washed.
The present invention provides a washing machine comprising a wash tub, a water-supply mechanism for supplying water into the wash tub, and a disposition section in which a solid antimicrobial agent containing an organic compound having a nitrogen-halogen atomic combination is disposed, the disposition section being provided in the water-supply mechanism, the antimicrobial agent being brought into contact with water thereby to release hypohalogenous acid into the water.
The fungi adherent to the wash tub and/or the laundry can be prevented from propagation since the water containing hypohalogenous acid is supplied into the wash tub in the aforesaid washing machine. Consequently, the laundry can sanitarily be washed.
In a first preferred form, the organic compound comprises any one or a mixture of a brominated hydantoine compound, a chlorinated hydantoine compound, and an iodinated hydantoine compound. Further, the organic compound preferably comprises a brominated isocyanuric compound.
In a second preferred form, the water-supply mechanism includes a water-supply path for supplying the water from a water source to the wash tub, and the disposition section is provided in the midst of the water-supply path. In this construction, the washing machine further comprises a filter provided downstream with respect to a portion of the water-supply path on which the disposition section is provided. When the antimicrobial agent is collapsed and part of the agent flows with water into the wash tub thereby to adhere to laundry, there is a possibility that the laundry may be decolorized. The aforesaid construction, however, can prevent the antimicrobial agent from flowing into the wash tub.
In a third preferred form, the water-supply mechanism includes a water-supply path for supplying the water from a water source to the wash tub, and the water-supply path includes a antimicrobial water supply path provided with the disposition section and an normal water supply path provided with no disposition section. The antimicrobial water supply path or the normal water supply path can be selected according to a degree of soil in the laundry, for example. In this case, the washing machine preferably comprises a control device selectively executing an antimicrobial water supply mode in which water having passed through the antimicrobial water path is supplied into the wash tub in a wash or rinse step and a normal water supply mode in which water having passed through the normal water path in the wash or rinse step. The control device preferably carries out the wash step or rinse step under the antimicrobial water supply mode for a longer time than under the normal water supply mode. In this arrangement, water containing hypohalogenous acid is supplied through the antimicrobial water path into the wash tub in the antimicrobial water supply mode so that the wash or rinse step is carried out. Since the wash or rinse step is performed for a longer period of time than under the normal water supply mode, the hypohalogenous acid can sufficiently accomplish the antimicrobial function.
In a fourth preferred form, the control device supplies into the wash tub the water having passed through the normal water supply path and thereafter supplies into the wash tub the water having passed through the antimicrobial water supply path under the antimicrobial water supply mode. Consequently, water containing high concentration of hypohalogenous acid can be diluted via the antimicrobial water supply path.
In a fifth preferred form, the washing machine further comprises a measuring element measuring a number of times of a antimicrobial water supply operation in which the water is supplied through the antimicrobial water supply path into the wash tub and an informing element informing that the number of times of the antimicrobial water supply operation measured by the measuring element has reached a limit number of times. Alternatively, the washing machine may further comprise a timing element measuring a time of an executed antimicrobial water supply operation in which the water is supplied through the antimicrobial water supply path into the wash tub and an informing element informing that the time measured by the timing element has reached a limit time. When the number of times or the time, of period of contact of the antimicrobial agent with water reaches a predetermined limit value, an organic compound contained in the antimicrobial agent is consumed such that hypohalogenous acid is not released. Accordingly, the antimicrobial agent needs to be supplemented or replaced by a new one. The aforesaid arrangement can reliably inform the user of a time for supplement or redisposition of the antimicrobial agent.
In a sixth preferred form, the water-supply mechanism includes a bathwater supply path provided for supplying bathwater into the wash tub and the disposition section is provided in a midst of the bath water supply path. Generally speaking, the bathwater contains a larger number of fungi than normal service water. The aforesaid construction, however, can limit propagation of fungi in the bathwater.
In a seventh preferred form, the antimicrobial agent has a predetermined dissolving speed when a water is at 25xc2x0 C., the dissolving speed being set so that an effective concentration of chloride contained in the water after contact with the antimicrobial agent is increased in a range of 0.1 ppm and 10 ppm relative to an effective concentration of chloride contained in the water before the contact with the antimicrobial agent. It is known that the antimicrobial effect is conspicuous when the concentration of chloride contained in wash liquid is at or above 0.5 ppm. Further, the concentration of chloride contained in service water is generally at or above 0.4 ppm. On the other hand, chloride produces strong smell when the concentration thereof is excessively high. The strong smell renders the user unpleasant. In the aforesaid arrangement, however, the concentration of chloride can be adjusted so that sufficient effect can be achieved without production of strong smell.
In an eighth preferred form, the water-supply mechanism includes a water-supply path for supplying the water from a water source to the wash tub, the water-supply path is provided with a water reservoir, and the disposition section is provided in the water reservoir. When water is reserved in the water reservoir, the antimicrobial agent in the reserved water releases hypohalogenous acid. Thus, the concentration of hypohalogenous acid contained in the water supplied into the wash tub can be adjusted by adjustment of a time for which the water is reserved in the water reservoir.
In a ninth preferred form, the washing machine further comprises a cassette case allowing water to pass therethrough and detachably attached to the disposition section. In this construction, the antimicrobial agent is accommodated in the cassette case. Consequently, the antimicrobial agent can be treated without direct touch therewith by hand.
In a tenth preferred form, the water-supply mechanism includes a bathwater supply path provided for supplying bathwater into the wash tub and a tap water supply path provided for supplying tap water into the wash tub. In this construction, the washing machine further comprises a control device selectively executing a bathwater supply operation in which water having passed through the bathwater supply path is supplied into the wash tub and a tap water supply operation in which water having passed through the tap water supply path. In this case, a concentration of hypohalogenous acid contained in the water in the wash water during the bathwater supply operation is set to be higher than a concentration of hypohalogenous acid contained in the water in the wash tub during the tap water supply operation.
In an eleventh preferred form, the antimicrobial agent contains a rust-proofing component for a material of iron system. The iron material can be prevented from being rusted by a strong acidifying force of the hypohalogenous acid released from the antimicrobial agent.